C#

private void SendMail_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "")
            {
                MessageBox.Show("Require, must content the row !!!");
            }
            else
                try
                {
                    obj_SMTPClient = new SmtpClient("smtp.gmail.com");
                    Obj_MailMsg = new MailMessage();
                    obj_Attachment = new System.Net.Mail.Attachment(textBox7.Text);
                    Obj_MailMsg.From = new MailAddress(textBox1.Text);
                    Obj_MailMsg.To.Add(textBox3.Text);
                    Obj_MailMsg.Body = textBox5.Text;
                    Obj_MailMsg.Attachments.Add(obj_Attachment);
                    Obj_MailMsg.Subject = textBox4.Text;
                    SmtpClient smtps = new SmtpClient("smtp.gmail.com", 587);
                    obj_SMTPClient.Credentials = new NetworkCredential();
                    obj_SMTPClient.Port = 587;
                    obj_SMTPClient.Credentials = new System.Net.NetworkCredential(textBox1.Text, textBox2.Text);
                    obj_SMTPClient.EnableSsl = true;
                    obj_SMTPClient.Send(Obj_MailMsg);
                    
                    obj_SMTPClient.EnableSsl = true;
                    obj_SMTPClient.Send(Obj_MailMsg);
                    MessageBox.Show("Message Successfuly Sent!!!");
                }
                catch
                {
                    MessageBox.Show("Failed to Send Message!!!");
                }
        }
		
		 private void EncryptionText_Click_1(object sender, EventArgs e)
        {
            cipherData = textBox6.Text;
            plainbytes = Encoding.ASCII.GetBytes(cipherData);
            // generating symmetric key
            desObj.GenerateKey();
            // generating vector
            desObj.GenerateIV();
            // choose other appropriate modes (CBC, CFB, CTS, ECB, OFB)
            desObj.Mode = CipherMode.CBC;
            // setting the padding mode
            desObj.Padding = PaddingMode.PKCS7;
            // --------------- ECRYPTION ---------------
            // memory stream used as a target to write enrypted data
            MemoryStream ms = new MemoryStream();
            // transforms and encrypts plaintext data to memorystream object
            CryptoStream cs = new CryptoStream(ms,
                desObj.CreateEncryptor(),
                CryptoStreamMode.Write);
            cs.Write(plainbytes, 0, plainbytes.Length);
            cs.Close();
            // getting encrypted data from memorystream to bytes
            cipherbytes = ms.ToArray();
            ms.Close();
            textBox5.Text = Encoding.ASCII.GetString(cipherbytes);
        }

        private void DecryptionText_Click_1(object sender, EventArgs e)
        {
            // --------------- DECRYPTION ---------------
            MemoryStream ms1 = new MemoryStream(cipherbytes);
            CryptoStream cs1 = new CryptoStream(ms1,
                desObj.CreateDecryptor(),
                CryptoStreamMode.Read);
            // allocate array of bytes equal on lenght with ciphertext array
            plainbytes = new Byte[cipherbytes.Length];
            // decrypt the ciphertext from previous section
            cs1.Read(plainbytes, 0, cipherbytes.Length);
            cs1.Close();
            ms1.Close();
            textBox5.Text = Encoding.ASCII.GetString(plainbytes);
        }